Boat hull

ABSTRACT

The hull bottom is shaped to form a longitudinal air-water channel which in the stern portion of the hull is divided into two transversely spaced air-water passages open at the transom. A pair of trim tabs are horizontally pivoted on the transom in such position that streams of air-water from the passages flow over as well as under the trim tabs.

United States Patent Boome I BOAT HULL [22] Filed: I Jan.7, 1971 [2]]Appl. No.: 104,585

[30] Foreign Application Priority Data 1 Oct. 17,1972

2,832,304 4/1958 Elyosius: et al ..1 14/665 H 2,773,467 12/1956 Bailey..l l4/66.5 l-l FOREIGN PATENTS OR APPLICATIONS 8,472 1908 Great Britain..1 14/665 P Primary Examiner-Andrew H. Farrell Attorney-Fetherstonhaugh& Co.

[57] ABSTRACT The hull bottom is shaped to form a longitudinal airwaterchannel which in the stern portion of the hull is divided into twotransversely spaced air-water passages open at the transom. A pair oftrim tabs are horizontally pivoted on the transom in such position thatstreams of air-water from the passages flow over as well as under thetrim tabs.

8 Claims, 6 Drawing Figures Feb. 3, 1970 Canada ..073,870

[52 us. Cl .Q ..ll4/66.5 P 511 Int. Cl. ..B63b 1/28 58 Field of Search..1 I4/66.5 P, 66.5 H

[56] I References Cited UNITED STATES PATENTS 3,450,090 6/1969 Best..114/02x I8 I I8 PATENTEDnm 17 m2 sum 1 OF 3 INVENTOR Martin W. BOUMEPATENT AGENTS PATENTEDum 17 m2 3 6 98'. 343

sum 2 or 3 INVENTOR Martin W. BOOME idZLEvfi Z 6 PATE T AGENTS BOAT HULLThis invention relates to new and useful improvements in boat hullsequipped with trim tabs at the stern thereof for the purpose oflevelling the boat in water and raising or lowering the bow duringoperation, so that effective control is obtained particularly in roughwater or at high speeds.

Although it is common in the art to provide trim tabs at the stern, suchconventional trim tabs are usually mounted at or above the lower edge ofthe transom close to the water line, with the result that waterupflowing past the bottom of the hull affects only the bottom surface ofthe trim tabs. Consequently, since the trim tabs are not disposed trulywithin the water stream, their efficiency. is not fully realized in theconventional arrangement.

The principal object of the invention is to substantially increase theoperating efficiency of and the control afforded by the trim tabs, thisbeing attained by the provision of an especially shaped hull bottomwhich has two transversely spaced air-water passages in the sternportion thereof, and mounting the trim tabs on the transom in suchposition that streams of air-water from such passages flow over as wellas under the trim tabs, thus enabling both the upper and lower surfacesof the trim tabs to be affected by the air-water stream for much moreefficient operation and better control than was heretofore possible.

With the foregoing more important object and features in view and suchother objects and features which may become apparent as thisspecification proceeds, the invention will be understood from thefollowing description taken in conjunction with the accompanyingdrawings, wherein like characters of reference are used to designatelike parts, and wherein:

I FIG. 1 is an underside perspective view of the boat hull in accordancewith the invention;

FIG. 2 is abottom plan view thereof;

FIG. 3 is a group illustration diagramatically showing cross-sections ofthe hull in the planes designated as 0, l, 2, 3, 4, 5, 6, 7 and 8 inFIG. 2;

FIG. 4 is an end elevatio'nal view of the hull, taken from the stern,and showing the trim tabs of the invention applied to the transom; and

FIG. 5 is a fragmentary vertical sectional view, taken substantially inthe plane of the line 5-5 in FIG. 4, and showing the trim tab actuatingmeans;

FIG. 6 is an end elevation similar to FIG. 4 but showing a singleair-water passage and a single trim tab.

Referring now to the accompanying drawings in detail, and moreparticularly to FIGS. 13, the boat hull designated generally as 10 is abarge-type hull, although this is not at all important from thestandpoint of the invention and it is to be understood that for allpractical purposes the forward portion of the hull may have the shape ofthe conventional tapered bow. The important feature of the invention isthat the bottom of the hull is especially shaped to provide alongitudinal air-water channel 21, which in the stern portion of thehull bottom is divided into two transversely spaced airwater passages13, which are open at the transom 14 of the hull.

Preferably, the aforementioned hull bottom shape is obtained byproviding the bottom along its side portions with a pair of longitudinalskid members which define the air-water channel 12 therebetween andextend along the outside of the air-water passages 13 to the transom 14.At the inside the passages 13 are shown to be transversely separated bya depressed, convex center portion 16 of the stern region of the hullbottom, it being understood that as the boat moves through water, anair-water stream passes through the channel 12 in the forward portion ofthe hull bottom and then becomes divided to flow rearwardly through thetwo transversely spaced passages 13 in the stern portion, past thetransom 14. Such division of the air-water stream is effected graduallyby the progressive, rearwardly increasing prominence of the depressedcenter portion 16 of the hull bottom, which makes the passages 13progressively more pronounced in the aft direction, as will be readilyapparent from FIG. 3, so that by the time the divided air-water streamsin the passages 13 reach the transom, they are well defined.

If desired, additional longitudinal skid members (not shown) may beprovided in the hull bottom, inboard of and parallel to the skid members15, such additional skid members being located approximately along theinside of the passages 13.

Two transversely spaced trim tabs 17 are disposed in a specific relationto the especially shaped hullbottom as already described, this being sothat the trim tabs, which are hinged to the transom 14 by horizontalpivot means 18, are located directly within air-water streams flowingrearwardly through the passages 13 past the transom. In other words, thepivot means 18 of the trim tabs are located on the transom end of theskid members 15 and of the depressed center portion 16 of the hullbottom so that the pivot axis of the trim tabs is disposed in ahorizontal plane which intersects the passages 13, as will be apparentfrom FIGS. 4 and 5. Consequently, with the pivot axis of the trim tabsbeing spaced downwardly from the roof of the passages 13, air-waterstreams from these passages will flow over as well as under the trimtabs, thus subjecting both the upper and lower surfaces of the the trimtabs to the airwater stream effect. In this manner the trim tabs aremuch more efficient in operation and much better control of the boat inwater is obtained than is possible with conventional trim tabs which areaffected by water flow only on their lower surfaces.

The trim tabs 17 may be raised and lowered about their pivots 17 in anysuitable manner, as exemplified in FIG. 5 where each trim tab isactuated by a suitable power source 19 inside the hull 1.0, the powersource being connected to articulated linkage 20 passing through anopening 21 in the transom 14. At the outside of the transom the linkage20 is connected to a link 22 which is pivoted to the trim tab 17 as at23, so that the trim tab may be raised or lowered by actuation of thepower source 19. Manifestly, a separate power source and separatelinkage are provided for the two trim tabs, so that they may be raisedor lowered independently of each other.

With further reference to the hull bottom configuration, it may be notedthat the hull sections in FIG. 3 are shown for illustrative purposesonly and may be modified in any desired manner, as long as the shape ofthe hull bottom is such as to produce two transversely spaced air-waterstreams past the stern to flow both over and under the trim tabs.

The modification shown in FIG. 6 takes care of boat hulls in which twoengines and propellers are employed for propulsion. in this applicationthere would be provided on the under side of the hull a single air-waterchannel 13a located longitudinally on the centerline of the hull, and asingle trim tab 17a would be provided aligned with the channel 13a.

The air-water channel 13a would extend forwardly from the rear of thehull in the same manner as the pair of channels 13 shown in FIG. 3.

What I claim is:

l. The combination of a boat hull having a bow portion and a sternportion and including a bottom and a transomysaid bottom being shaped toprovide in the stern portion a pair of transversely spaced longitudinalpassages which are open at the transom and extend forwardly to open atthe bow so that when the hull moves through water, a mixture of waterand air flows rearwardly through said passages, and a pair oftransversely spaced trim tabs pivoted to said transom in longitudinalalignment with and rearwardly of the respective passages, said trim tabshaving a horizontal pivot axis disposed in a plane which intersects saidpassages in downwardly spaced relation from the roof of the passages sothat the air-water mixture flowing through the passages flows over aswell as under the trim tabs.

2. The combination as set forth in claim 1 wherein said hull bottomincludes a pair of longitudinal skid members extending along the outsideof the respective air-water passages, said passages being transverselyspaced from each other at the inside thereof by a depressed centerportion of the hull bottom.

3. The combination as set forth in claim 2, together with horizontalpivot means mounting said trim tabs on said transom, said pivot meansbeing located at the transom end of said skid members and of saiddepressed center portion of the hull bottom.

4. The combination as set forth in claim 2, wherein said skid membersalso extend forwardly along the hull bottom and define between theirforward portions a longitudinal air-water channel which in the sternregion of the hull is separated into said transversely spaced passagesby said depressed center portion of the hull bottom.

5. The combination as set forth in claim 1 together with means forraising and lowering said trim tabs about their horizontal pivot axis.

6. The combination as set forth in claim 1, together with a propeller atthe stern of said hull, said propeller being disposed centrally in thespace between said airwater passages.

7. The combination of a boat hull having a bow portion and a sternportion and including a bottom and a transom, said bottom being shapedto provide a central longitudinal passage which is open at the transomand extends forwardly to open at the bow so that when the hull movesthrough the water, a mixture of water and air flows rearwardly throughsaid passage, and a transverse trim tab pivoted to said transom inlongitudinal alignment with and rearwardly of said passage, said trimtab having a horizontal pivot axis disposed in a plane which intersectssaid passage in downwardly spaced relation from the roof of the passageso that the air-water mixture flowing through the passage flows ov raswell as nder the trim ab.

The combination as set orth in claim 7, together with a pair ofpropellers at the stern of said hull, said propellers being spacedtransversely to opposite sides of said central passage.

1. The combination of a boat hull having a bow portion and a sternportion and including a bottom and a transom, said bottom being shapedto provide in the stern portion a pair of transversely spacedlongitudinal passages which are open at the transom and extend forwardlyto open at the bow so that when the hull moves through water, a mixtureof water and air flows rearwardly through said passages, and a pair oftransversely spaced trim tabs pivoted to said transom in longitudinalalignment with and rearwardly of the respective passages, said trim tabshaving a horizontal pivot axis disposed in a plane which intersects saidpassages in downwardly spaced relation from the roof of the passages sothat the air-water mixture flowing through the passages flows over aswell as under the trim tabs.
 2. The combination as set forth in claim 1wherein said hull bottom includes a pair of longitudinal skid membersextending along the outside of the respective air-water passages, saidpassages being transversely spaced from each other at the inside thereofby a depressed center portion of the hull bottom.
 3. The combination asset forth in claim 2, together with horizontal pivot means mounting saidtrim tabs on said transom, said pivot means being located at the transomend of said skid members and of said depressed center portion of thehull bottom.
 4. The combination as set forth in claim 2, wherein saidskid members also extend forwardly along the hull bottom and definebetween their forward portions a longitudinal air-water channel which inthe stern region of the hull is separated into said transversely spacedpassages by said depressed center portion of the hull bottom.
 5. Thecombination as set forth in claim 1 together with means for raising andlowering said trim tabs about their horizontal pivot axis.
 6. Thecombination as set forth in claim 1, together with a propeller at thestern of said hull, said propeller being disposed centrally in the spacebetween said air-water passages.
 7. The combination of a boat hullhaving a bow portion and a stern portion and including a bottom and atransom, said bottom being shaped to provide a central longitudinalpassage which is open at the transom and extends forwardly to open atthe bow so that when the hull moves through the water, a mixture ofwater and air flows rearwardly through said passage, and a transversetrim tab pivoted to said transom in longitudinal alignment with andrearwardly of said passage, said trim tab having a horizontal pivot axisdisposed in a plane which intersects said passage in downwardly spacedrelation from the roof of the passage so that the air-water mixtureflowing through the passage flows over as well as under the trim tab. 8.The combination as set forth in claim 7, together with a pair ofpropellers at the stern of said hull, said propellers being spacedtransversely to opposite sides of said central passage.